[Nobadeer]

I just watched the replay of the W 1500. Ledecky swam one of her fastest times, yet won by "only" 5 seconds. High quality final. She blazed out to 4:02 in the first 400, then 4:08 for the next 400, then a 4:09, and finally a 3:07 for the final 300, helped by 30.2 for the last 50. 

She held 40 to 41 strokes per lap. A decent rec swimmer might hold ~ 40 strokes per 50 meter lap, for a couple or few hundred meters - at half her speed!

[Nobadeer]

I just watched the replay of the W 1500. Ledecky swam one of her fastest times, yet won by "only" 5 seconds. High quality final. She blazed out to 4:02 in the first 400, then 4:08 for the next 400, then a 4:09, and finally a 3:07 for the final 300, helped by 30.2 for the last 50. 

She held 40 to 41 strokes per lap. A decent rec swimmer might hold ~ 40 strokes per 50 meter lap, for a couple or few hundred meters - at half her speed!